<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>Document</title>
 <style>
 select{
  width: 80px;
  margin: 5px;
 }
 </style>
 <script>
  // 省份数组
 var provinceArr = ['上海', '江苏', '河北'];
   // 城市数组
   var cityArr = [
   ['上海市'],
  ['苏州市', '南京市', '扬州市'],
  ['石家庄', '秦皇岛', '张家口']
 ];
   // 区域数组
   var countryArr = [
   [
    ['黄浦区', '静安区', '长宁区', '浦东区']
   ],
   [
    ['虎丘区', '吴中区', '相城区', '姑苏区', '吴江区'],
    ['玄武区', '秦淮区', '建邺区', '鼓楼区', '浦口区'],
    ['邗江区', '广陵区', '江都区']
   ],
   [
    ['长安区', '桥西区', '新华区', '井陉矿区'],
     ['海港区', '山海关区', '北戴河区', '抚宁区'],
     ['桥东区', '桥西区', '宣化区', '下花园区']
    ]
   ];
   window.onload = function(){
   var province = document.getElementById('province');
   var city = document.getElementById('city');
   var country = document.getElementById('country');
   createOption(province, provinceArr);
   province.onchange = function(){
    city.length = 0;
    createOption(city, cityArr[this.selectedIndex]);
    city.onchange();
   }
   city.onchange = function(){
    country.length = 0;
    createOption(country, countryArr[province.selectedIndex][this.selectedIndex]);
   }
   province.onchange();
   }
   function createOption(obj, data){
   for (var i = 0; i < data.length; i++) {
    var newOption = new Option(data[i], data[i]);
    obj.add(newOption, null);
   }
   }
 </script>
</head>
<body>
 省份<select name="" id="province"></select>
 市区<select name="" id="city"></select>
 县城<select name="" id="country"></select>
</body>
</html>